Arrangement for transmitting and receiving wireless messages



May 5, 1942. A. LEYN 2,281,982 ARRANGEMENT FOR TRANSMITTING ANDRECEIVING WIRELESS MESSAGES Filed 001;. 5, 1940 4' 7 Yifffii I I l v l lAAHHAQER CUNVPO 6000kC I 600m 1 w m I I .l I L REC'E/VER INVENTORALBAFCHT LEYN ATTORNEY Patented May 5, 1942 ARRANGEMENT FOR TRANSMITTINGAND RECEIVING WIRELESS MESSAGES Albrecht Leyn, Berlin, Germany,

funken Gesellschaft fiir Drahtlose assignor to Tele- TelegraphicZehlendorf, Osteweg, Berlin, Germany, a corporation of GermanyApplication October 5, 1940, Serial No. 359,852 In Germany July 5, 19397 Claims.

The technical problem exists so to build a transmitter and receiver thatthe transmitter and receiver operate on the same wave frequency, wherebythe transmitter shall not contain a selfexcited generator, but the localoscillator provided at the receiver side shall be employed at the sametime for controlling the frequency of operation of the transmitterstages. This problem presents itself in part in view of the fact thatthe provision of oscillators having an absolutely constant frequencyinvolves a very complicated ensemble especially in the case of extremelyshort waves. The local oscillator of the receiver must have a constantfrequency and, therefore, the question arose as to whether it may bepossible to utilize in any suitable way the heterodyning oscillation forcontrolling the transmitter. Since, in accordance with the problem set,the transmitter oscillation is to be equal to the receiving oscillation,it is obvious that the heterodyning frequency cannot be used unchangedas control frequency and it is here where the present invention sets in.The receiver contains an intermediate-frequency stage whose frequencycorresponds with the difference of the frequencies of the arriving waveand of the heterodyning oscillation. This intermediatefrequency stagenow may be provided with a feedback whereby it can also operate asgenerator, namely for the intermediate frequency. Such a generator canbe made to operate at constant frequency in a much simpler way than agenerator for shorter waves inasmuch as the intermediate-frequency stageis arranged from oscillatory circuits having a favorable constancy offrequency of operation. Now, in order to control the transmitter, theheterodyning oscillation is combined with the oscillation of theintermediate-frequency stage which operates as a generator. As caneasily be seen, the sum wave furnishes the transmitting frequency. Thissum wave is then applied to the transmission aggregate whereby thetransmitter stage is controlled. The present invention will now beelucidated in reference to the accompanying drawing.

In the drawing, the circuits in the rectangle E is the receiver, thosein the rectangle S is the transmitter. The transmitter structurecomprises an amplification stage V and a control stage St. The receiverhas a high-frequency amplifier stage II, a local oscillator stage U andan intermediate-frequency stage Z. Keying or modulation of thetransmitted wave may occur in stage V or St. The drawing shows that theintermediate-frequency stage contains a feedback connection R which canbe actuated by a key T. The receiver output may be derived in stage Z.Furthermore, a mixer stage M is provided connected to U and Z and to Vby way of St. Assuming the transmitter wave and the receiving wave havea frequency of 6000 kilocycles and that the local oscillator U producesa frequency of 5900 kilocycles, then an intermediate frequency ofkilocycles will be obtained. If the feedback is operated, theintermediate-frequency stage oscillates in the frequency 100 kilocycles.These oscillations together with the 0scillations of the localoscillator U are applied to the mixer tube M and furnish again theoutput oscillation of 6000 kilocycles which, as is indicated by theconnection, is applied to the control transmitter St. With thisarrangement a short wave oscillator having constant frequency can bedispensed with. That is, the stage Z operating at a lower frequency canbe readily stabilized as to frequency of operation. Aside from the factthat the intermediate frequency stage, if it operates as a generator,can be more readily adapted for constant frequency than an oscillatorfor short waves, variations of the intermediate frequency, especially inrespect to the transmitter frequency to be produced, play but anunimportant part. The arrrangement according to the present invention,can be employed for telegraphic operation as well as for telephonicoperation. In case of the telegraphic operation in order to give thesignals it is sufficient to operate the key T which connects anddisconnects the feedback, while in the case of telephonic operation, itis obvious that during the entire time of speaking the said key must beclosed, i. e., to provide feedback and cause the oscillator tooscillate. It is obvious that the various modes of construction maygreatly differ from one another. It'is likewise obvious that in a mannerknown as such further amplifier stages and relays may be provided.

What is claimed is:

1. In a signalling system, receiving means including an amplifier forreceiving and amplifying signalling energy of a first frequency, anoscillation generator for producing wave energy of a secondsubstantially fixed frequency, a mixing circuit and intermediatefrequency stage coupled to both of the aforesaid means for beating saidwave energies to produce signalling energy of a third frequency, andtransmitting means including means for generating oscillations of saidthird frequency in said intermediate frequency stage, a detector coupledto said oscillation generator and said intermediate frequency stage forbeating said generated oscilaltions of said third frequency with waveenergy of said second frequency to produce wave energy of said firstfrequency and an amplifier and a wave energy radiator coupled to saidsecond detector.

2. A system as recited in claim 1 including means coupled with saidintermediate frequency stage when operated as a generator for modulatingthe wave energy of said third frequency.

3. In a transmitter and receiver, a first aerial for translating radiantenergy into electrical currents, a second aerial for translatingelectrical currents into radiant energy, a source of oscillations, awave mixer and intermediate frequency stage coupled to said first aerialand to said source of oscillations, a circuit for producing regenerationin said intermediate frequency stage, a second wave mixer coupled tosaid second aerial, a coupling between said second wave mixer and saidintermediate frequency stage, and a second-separate coupling betweensaid second wave mixer and said source of oscillations.

4. A system as recited in claim 3 including wave modulating means in thecoupling between said second aerial and said second wave mixer.

5. A system as recited in claim 3 including means connected with saidintermediate frequency stage for modulating the generated wave energy inaccordance with signals.

6. A system as recited in claim 3 including wave amplifying means andwave modulating means in the coupling between said second named aerialand said second wave mixer for modulating the electrical currentstranslated by said second aerial in accordance with signals.

7. In a signalling system, a wave receiver including a stable source ofoscillations and a wave converter cooperating to provide beat energymodulated in accordance with received signals, a beat frequency stagefor said beat frequency, and means for providing a carrier of thefrequency of said received signals for transmission purposes includingmeans for operating said beat frequency stage as an oscillationgenerator and a wave frequency converter coupled to said stable sourceof oscillations and to said intermediate frequency stage to provide saidcarrier.

ALBRECHT LEYN.

